This invention relates to a pulper which converts bulky, solid wastes to a uniform moist pulp.
In restaurants, food service establisments, cafeterias and the like the refuse comprising scrap food, napkins, bags, boxes, milk cartons, etc., are typically deposited in plastic bags. When the bags are filled the tops are tied, the bags stored and ultimately removed. Waste in this form takes considerable storage space. Also, when it is trucked away, most of the volume carried by the trucks is air.
To reduce the volume, many establishments, particularly food service establishments, use a device known as a pulper which reduces the volume of waste approximately 75%. Briefly, all refuse is pulverized to form a slurry and then the pulp is extracted from the slurry. One such pulper known in the food equipment industry is exemplified in U.S. Pat. No. 3,188,942.
These pulpers generally comprise a pulverizing section to disintegrate the materials forming a slurry and a separating section to remove the solids from the slurry. The separating section includes an auger received in a cylindrical screen. The auger carries the slurry and de-waters the same to form a moist pulp and a liquor.
In some pulpers currently used, the auger has a tendency to jam when solids build up occurs between the crest of the auger and the surrounding screen. When this occurs the pulper must be shut down and the obstruction removed, a process requiring the dismantling of the unit.
The use of large quantities of make up water to keep the carrier liquid `fresh` requires essentially that a volume of liquid proportional to the make up water continuously discharge down the drain at the same time maintaining a constant volume of carrier water in the system. Present pulpers can only add that amount of water removed with the dewatered pulp if the carrier volume in the system is to remain constant.
The present invention is directed to an apparatus and method which broadly is an improvement of the prior art pulping apparatus and which minimizes to the point of elimination the jamming of the auger and prevents clogging of the drain when desirable large quantities of make up water is used. Broadly, the invention in one embodiment, recycles a portion of the liquor extracted from the pulp as a jet stream into the upstream end of the auger to create turbulence thereby preventing increased solids contents from forming. In a preferred embodiment, a restricted flow path is formed to limit the size of the particulate material flowing to the base of the auger.
In the preferred embodiment, a second by-pass system, considerably larger in volume than the make-up water added, is introduced in the drain chamber and directed against the screen. The more or less exact quantity of the make-up water goes down the drain chamber stand pipe and the balance flows back into the pulper chamber through the screen holes kept clean from outside debris by the by-pass stream. Thus, the equilibrium quantity of the carrier liquid is maintained even though excess make-up water is continuously added to keep the carrier liquid from `thickening` from garbage during constant use.